titanium costs heaps more to buy and make stuff from. but it is heaps stronger and still looks awesome.
No.... titanium is better in shear, and is much more ductile (better fracture toughness) CF is significantly better in tension, which is why they weave it (to spread out the shear forces. The resin is the matrix o the composite, which holds it together, and protects it form impacts.
Also, I like Magnesium. It's the lightest structural metal. It's got a strength-to-weight ratio similar to aluminium, so it's not as good as titanium. It's also a pretty sweet alloying metal, and one of the main reasons 6XXX and 7XXX series aluminium are stronger than 1XXX (pure aluminium with uncontrolled impurities)
That said, Titanium is pretty awesome. But if we're going that far out, why not extruded brass matrix filled up with aluminum? It's almost as strong, lighter, and cheaper. Looks excellent, too: would make an amazing keycap.